Asphalt compositions



United States Patent ASPHALT coMPosnmNs Lowell T. Crews, Homewood, and Mathew L. Kalinowski, Chicago, Ill., and Frederick H. MacLaren, Munster, Ind., assignors to Standard Oil Company, Chicago, 111., a corporation of Indiana No Drawing. Application June 28, 1952, Serial No. 296,252

14 Claims. (Cl. 106-473) The present invention is directed to improvements in bitumen compositions, and particularly to improvements in mineral aggregate coating compositions, and more particularly relates to bitumen compositions having improved adherence to damp or Wet mineral aggregates.

Residual oils and/or bituminous materials used in the preparation of pavements and roads do not coat and adhere well to mineral aggregates unless the aggregate is substantially dry, and for this reason in conventional pavements or road construction practice, it is customary to dry the mineral aggregate by suitable well known methods. Furthermore, water entering the road or pavement during service may have a detrimental elfect in that it may displace the oil or bitumen from the surface of the aggregate and thus diminish the bonding effect of the oil and7 or bitumen. This materially shortens the life of the road or pavement requiring frequent repairs and is, there fore, uneconomical.

Mineral aggregates employed in road or pavement construction range in character from hydrophilic to hydrophobic. In general, siliceous and acidic minerals, such as sands and gravels, tend to be hydrophobic while calcareous alkaline minerals, such as limestone, tend to be hydrophilic. it has been observed that the mineral aggregates appear to have a greater attraction for water than for oil or bitumens and that it is difficult to obtain by conventional methods complete or satisfactory coating of aggregates by oil or bitumen when Water is present. Furthermore, even though satisfactory coating is obtained by using dry aggregates, the oil or bitumen tends to be displaced if water enters the pavement or road.

It is known that the coating of damp or Wet mineral aggregates by oil or bitumen may be effected and the resistance of the coating to displacement or stripping by water may be improved by treating the aggregate with small amounts of water-soluble soap of a fatty acid in conjunction with Water-soluble salt of a polyvalent heavy metal or activator. For optimum results with these reagents the relative amounts of the two reagents must be carefully adjusted. Thus, when a divalent heavy metal is used as activator, the amount of soap used should be .substantially one mole per mole of activator; with a trivalent metal, between one and two moles of soap per mole of activator. Use of larger amounts of soap than this diminishes the effect obtained, and this diminution of effect increases with excess of soap over the proportions given until when the amount of soap becomes equivalent to the activator, i. e., two moles of soap per mole of divalent metal or three per mole of trivalent metal, the beneficial effect of the reagent substantially disappears.

The above method has the disadvantage that therelative amount of soap and polyvalent heavy metal activator are critical and must be carefully adjusted for optimum results. Use of an excess of soap over the optimum amount diminishes rather than enhances the effect obtained; the use of excess heavy metal to avoid the danger of excess soap is not harmful but increases the cost. Furthermore, the two reagents must be weighed or measured and added Patented Aug. 231, 1%56 to each batch, as neither is soluble in the oil or bitumen; While this disadvantage may be partially overcome under favorable conditions by using in place of the soap a fatty acid dissolved in the oil or bitumen, this expedient is very effective only under favorable conditions of low moisture content of the aggregate, adequate and efficient mixing, etc. Under the conditions which are not at all severe, such as appreciable amounts of water and/or facilities for only moderately efficient mixing, fatty acids appear not to be sufficiently soluble in Water to reach and react with the heavy metal ion to the required extent, and if added directly to the mixture or dissolved in the oil or bitumen are practically without effect.

Another important disadvantage of the above method is that a heavy polyvalent metal salt must be used with the soap. Furthermore, it has been found that while some limestones appear capable of adsorbing or reacting with polyvalent heavy metal ions and accordingly respond to some degree to the above method, a great many others do not, and with these it is difiicult or impossible to obtain a good coating by the above method. Also, since the foregoing method is not in general satisfactory with limestone, a great many natural mixed aggregates such as gravels containing both siliceous and calcareous particles will have only a portion of the particles coated.

In addition to the use of polyvalent fatty acid soaps in bitumens as mineral aggregate coating agents, certain organic nitrogen compounds, such as those obtained by re acting a polyamine with a fatty acid under conditions to form essentially amides, have been used for this purpose. However, although the amide-type asphalt additives are effective coating agents for acidic mineral aggregates, such as sands and gravels, they are ineffective on alkaline mineral aggregates, such as limestone.

It is an object of the present invention to provide a bituminous material having improved coating properties. It is also an object of the present invention to provide an oil or bitumen composition which will adhere to wetted acidic and alkaline mineral aggregates. Another object of the present invention is to provide a coating composition for acidic and alkaline mineral aggregates which will not be stripped therefrom by aqueous liquids. Still another object of the invention is to provide a coating composition for acidic and alkaline mineral aggregates which can be applied without the necessity of drying the mineral aggregate and which will adhere thereto even in a wet condition. Another object of the invention is to provide a method of preventing stripping of the coating composition from acidic and alkaline mineral aggregates by water after the road and/or pavement is constructed. A further object of the invention is to provide a method of promoting the adherence of oil bituminous materials to siliceous and limestone aggregates without the necessity of drying the same. Other objects and advantages of the invention will become apparent as the following description thereof proceeds.

In accordance with the present invention bitumens such as for example road oils and asphalts having improved mineral aggregate coating properties, especially with respect to wet acidic and alkaline mineral aggregates are obtained by incorporating in such bitumens from about 0.25% to about 5%, and preferably from about 0.5% to about 3%, by volume, based on the bitumen content, of the oil-soluble product obtained by reacting, under conditions to avoid amidation, an aliphatic polyamine with a polymerized high molecular Weight unsaturated fatty acid or fat acid of the type hereinafter described. The term high molecular weight unsaturated fatty acid or fat acid, as used herein refers to those acids having at least 10 carbon atoms. The polymerized acids contain at least one double bond per molecule and have molecular weights between about 400 and about 2000,

and preferably between about 500 and about 1500. Since amidation of amine soaps is brought about by the loss of water at high temperatures, the reaction of the aliphatic polyamine with the aforementioned polymerized acids is carried out at temperatures below about 265 F., preferably below about 240 F., and more preferably, at temperatures of from about 180 F. to about 225 F. to obtain a product essentially free of amido groups.

The glycerol esters of various carboxylic acids that are termed fatty acids or fat acids and occur in fats and oils of natural origin are often heated to effect a bodying of the oil and this results in a polymerization of the oils. A primary source for the polymerized fatty acids employed in the present invention are those residual acids obtained by methanolysis of semi-drying oils, such as for example, castor oil or soy bean oil, polymerizing the so-obtained methyl esters, removing unpolymerized compounds, saponifying the residual esters and freeing polymerized acids therefrom. When a soy bean oil is em; ployed, this results in a product consisting of polymers of linoleic acid, about 75% of which is the dilinoleic acid, and about 20% of the trilinoleic acid. The polymeric product has an acid number of about 190 to 200 and a molecular weight between about 500 and 900, or between 560 and 590 for the dibasic acid. (Calculated molecular weight of dilinoleic acid is 560; some higher polymers are present.) The average molecular weight of the trimeric fat acid is approximately 840. The acids are characterized by having a plurality of double bonds and can result from the polymerization of fatty oils in the form of the glycerides of the fat acids or other esters, for example, the methyl esters as hereinabove shown.

Several treatments may be employed to effect a polymerization of the oils. They can be, for example, polymerized by thermal treatment. They can also be polymerized by using a suitable polymerizing catalyst in which case the temperature will vary with the selection of the catalyst. A common procedure employed in the production of fat acids is described in Cowan et al. 2,450,940 patented October 12, 1948, in which a fatty oil is subjected to alcoholysis with monohydric alcohols whereby the glycerides of the fat acids are converted to the corresponding monohydric alcohol esters. These esters are polymerized. Other reaction products are distilled from the polymers and the polymeric acids are freed from the esters by hydrolysis. Other methods are described in the said patent and other methods will be pointed out in the specific examples for producing the said crude polymers or recovered poly-unsaturated dimerized acids.

A commercial process for preparing dimerized fat acids comprises the steps of heating unsaturated fat acids and a small amount of water to 330 C. to 360 C. at 85 to 400 pounds per square inch gauge for 3 to 8 hours and vacuum distilling the product. The acid polymer produced in this manner consists of about 85% of the dipolymer, and 12% higher polymers.

Various methods of obtaining polymerized fatty acids of the type herein-described are illustrated by the following examples:

EXAMPLE I A dimerized fraction of fat acids having a refractive index of 1.4753 to 1.4773 was obtained by fractionally distilling dimeric fat esters obtained from vegetable oils at temperatures between 150 C. and 200 C. at very low pressure, saponifying the distillate with alcoholic KOH and then neutralizing with acid. The dimerized fat acid obtained had a molecular weight of about 500 and an iodine number of 116.

EXAMPLE II Trimeric acids were obtained from a mixture of dimeric and trimeric esters produced by the heat polymerization of the methyl esters of soy bean oil at 300 C. for eighteen. to twenty hours. The crude esters were then molecularly;

distilled at 228 C. under very low pressures and the distillate fraction containing the trimeric esters saponified with alcoholic KOH and then neutralized with acid. The fat acid polymers obtained had a molecular weight of about 750 and an iodine number of 114.

EXAMPLE III Methyl esters of soy bean fat acids were polymerized in the presence of 2%, by weight, based on the esters, of hydrogen fluoride at a temperature of about C. to C. for one hour. The resultant product was washed to remove hydrogen fluoride and the non-polymerized esters removed by distillation under a vacuum of 0.4 milliliters of Hg to a maximum distillation temperature of 250 C. A yield of 70%, by weight, of mixed polymeric esters having a refractive index of 1.4825 at 30 C. and a color of 14 Gardner was obtained. The esters were saponified with alcoholic KOH and then neutralized to obtain free mixed polymeric fat acids. The mixture of higher fat acid polymers was a highly viscous product having a molecular weight of 1400 and an iodine number of 137.

EXAMPLE IV Crude fat .acids obtained from soy bean foots oil were polymerized in the presence of boron fluoride in the ratio of 4 grams of boron fluoride per grams of acid at a temperature of 200 C. for about two hours. The polymerized product separated from the catalyst had a refractive index of 1.483 at 33 C. and an acid value of 166. The polymer had a molecular weight of 650 and an iodine number of 75.

The amine reactant employed in preparing the additive of the present invention is an aliphatic polyamine, particularly an alkylene polyamine containing at least two primary amino nitrogen atoms. Examples of alkylene polyamine suitable for the herein described purpose are ethylene diamine, propylene diamine, diethylene triamine, diamylene triamine, triethylene tetramine, tripropylene tetramine, diethylenepropylene tetramine, tetraethylene pentamine, tetrabutylene pentamine, diethylenedipropylene pentamine, butylene diamine, dihexylene triamine, and the like, or mixtures thereof. For example, a suitable polyamine product is a crude diethylene triamine containing minor amounts of ethylene diamine and triethylene tetramine. Other suitable polyamines include those having the general formula RNH(CH2)3NH2 in which R is preferably a C10 to C18 aliphatic chain, and which are obtained by condensing the suitable amine with acrylonitrile and hydrogenating to the corresponding diamine. Commercially available polyamines of this type are those marketed by Armour and Company as Duomeens, which are prepared by the condensation of a dodecyl (Coco) amine or an octadecyl (tallow) amine with acrylonitrile followed by hydrogenation to the corresponding diamine product; these products are marketed as Duomeen C and Duomeen T, respectively.

In the preparation of the polymerized fatty acid and polyamine reaction product, it is preferable, although not essential, that the polymer be first dehydrated to obtain an essentially water-free product or a product having not more than about 0.5% Water. This can be readily accomplished by diluting the polymer with from about 10% to about 50% of a suitable hydrocarbon solvent, preferably a solvent rich in aromatic hydrocarbons, and by heating the diluted mixture at a temperature of about 210 C. to 290 F. While stirring and/or blowing with air or other suitable gaseous medium until the Water content has been reduced to the desired value. If desired, the diluent may be removed from the dehydrated polymerized fatty acid by suitable means such as by distillation under vacuum; however, we prefer to react the diluted polymer with the polyamine.

Aromatic-rich hydrocarbon solvents suitable for this purpose are preferably those having boiling points above about 220 F. at atmospheric pressure and includes mono nuclear aromatic hydrocarbons or condensed ring aromatics, such as naphthalenes and mixtures of the higher boiling mono-nuclear aromatic hydrocarbons and polynuclear aromatic hydrocarbons.

A preferred source of mixed aromatic hydrocarbons suitable for this purpose is a light catalytic cycle stock obtained from a powdered or a fluid-type catalytic-type hydrocarbon cracking operation, in which gas oil or heavier hydrocarbons are cracked at a temperature of 800 F. to 1050 F. under a pressure of about atmosphere to 50 pounds per square inch, and in the presence of suitable fluid or powdered catalyst, such as for example, sil-icaralumina, silica-magnesia and other well-known crackingcatalysts. A method of conducting a fluidized cracking operation is described in U. S. 2,341,193 issued to Fred W. Scheineman February 8, 1944. Fractions from the process heavier than gasoline, depending upon their boiling range, are commonly referred to as light catalytic cycle stock, heavy catalytic cycle stock and catalytic recycle resid, which usually are cycled to cracking. A light catalytic cycle stock particularly well suited as a diluent for the dehydration of the polymerized fatty acid is a fraction having an aromatic content of at least about 40% and a distillation range between about 425 F. and about 560 F. A typical analysis of a suitable light catalytic cycle stock shows the material to be composed substantially of about normal C12 to C parafiins, about 45% of other paraifins and naphthenes, and about 5% mono-nuclear aromatics,

which are mainly monoto hexa-alkylated benzenes, and

about 40% polynuclear aromatics which are mainly alky-l naphthalenes, largely methylated naphthalenes. While we prefer to use a light catalytic cycle stock of the type described, hydrocarbon fractions from other catalytic conversion processes or thermal hydrocarbon conversion processes are suitable provided they have an aromatic content of at least 20% and a distillation range above about 220 F.

The polymerized fatty acid preferably but not necessarily in solution in the light catalytic cycle stock or other suitable diluent is reacted with the polyamine in the ratio of from about :1 to about 5:1, and preferably in a ratio of from about 12:1 polymer to the polyamine at a temperature below about 265 F., and preferably of from about 180 F. to about 225 F., for not more than about one and one-half hours, preferably one-half hour, and the temperature then reduced as rapidly as possible to about 170 F., or lower. By conducting the reaction in the manner described herein and maintaining the finished product until ready for use at a temperature below about 150 F., and preferably below about 140 R, an eflicient stable coating agent essentially free of amido groups is obtained.

Under some conditions the polyamine-polymer reaction product even in solution in the diluent, such as the light catalytic cycle stock, may cause some difiiculty in the pumping and transferring thereof from containers and through pipelines, especially when the temperatures fall below about 70 F.80 F. This condition can be corrected by adding from about 5 parts to about 15 parts of an aliphatic alcohol of less than about five carbon atoms, preferably isopropyl alcohol, to the mixture of polymerized fatty acid polyamine reaction product and hydrocarbon diluent. A suitable mixture comprises from about parts to about 60 parts of the polymer-polyamine reaction product, from about parts to about 25 parts of the light catalytic cycle stock, and from about 5 parts to about 15 parts isopropyl alcohol.

The asphalt component of the herein-described composition may be of any bitumen which is useful for the coating of mineral aggregates used in the making of roads, highways, etc., or for the coating of other materials or surfaces Where a Water-resistant bond between the surface and the asphalt is advantageous or necessary. The term asphalt as employed herein is intended to be synonymous with bitumen and to cover a liquid, semi-solid or 6 solid plastic bituminous material of the type employed in making or surfacing of highways and/ or pavements, caulking agents, sealing compounds, wa-ter impervious paints, roofing materials, etc. Such asphalts or bituminous materials are mixtures of hydrocarbons of natural or pyrogenous origin, and are usually derived from petroleum or coal but may occur as such in nature. Asphalts may be derived as distillation resids or cracking resids with or Without oxidation by air-blowing or by catalytic oxidation. The specific example of an asphalt of the type usually employed in the preparation of highways, etc., is a petroleum residuum cutback, fluxed with a light aromatic diluent boiling in the range of 400 F. to 700 F. .to .give a cutback product of the following specifications:

Cutback asphalt 1 Not less than.

2 Not more than.

Normally solid paving asphalt of the 40- 200 penetration grades commonly used in road building fall within the following specifications:

Penetration at 77 F 40-200.

A. S. T. M. ductility at 77 F Not less than 100.

Oliensis spot test Negative.

Solubility in CCl4, percent Not less than 99.5.

Specific gravity at F Not less than 0.990

Flash, F. (C. O. C.) Not less than 475.

Loss on heating 50 grams for five hours at 325 F., percent Penetration of residue at 77 F., percent of original penetration Not less than 0.5.

Not less than -75.

The effectiveness of the herein-described polymerized fatty acid polyamine reaction products in enhancing the adhesion of asphalts to wet mineral aggregates i's demonstrated by the data in Table I by subjecting blends of an asphalt and a polymerized fatty acid polyamine reaction product of the type above described to the following test:

20 grams of Ottawa sand or 20 grams of a 20 to 35 mesh limestone are weighed into a 2 oz. container and covered with one-half inch distilled water, the mixture then shaken for thirty seconds and the extent of coating is determined by visual inspection; the results are expressed as Percent coated.

In the above table the control was a cutback asphalt having the specifications described above.

Additive A was a polymerized fatty acid-polyamine reaction product prepared as follows:

21.4 parts of polymerized fatty acid of equivalent weight 339 was mixed with 10 parts of light catalytic cycle stock and 2 parts of ethylenediamine having an equivalent weight of 31.6 and the mixture stirred and blown with air at 235 F. for 90 minutes.

Additive B was a commercial asphalt additive comprising essentially a fatty acid-polyamine amide.

It will be noted that whereas the additive of the present invention was effective on both sand and lime stone aggregates, the commercial additive was inefiective on limestone.

Although the polymerized fatty acid-polyamine reaction products are heat stable at temperatures as high as 230 F., and exhibit essentially no degradation with respect to coating and stripping efliciency, it is advisable to limit the blending and/or storage temperature for the fortified asphalts to temperatures not in excess of about 150 F., and preferably at temperatures not in excess of 140 F. Likewise, asphalts containing the herein-described asphalt additives should preferably be applied at temperatures not in excess of about 230 F.

Percentages expressed herein are volume percentages unless otherwise specified.

While the present invention has been described by reference to specific embodiments thereof, these are given by way of illustration only and the invention is not to be limited thereto but includes within its scope such modifications and variations as come within the spirit of the appended claims.

We claim:

1. A composition of matter consisting essentially of a major proportion of a bitumen, and from about 0.25% to about 5% of the oil-soluble reaction product substantially free of amido groups obtained by reacting an alkylene polyamine having 2 to 6 carbon atoms in the alkylene group and a polymerized unsaturated fatty acid from vegetable oils having a molecular weight between about 400 and 2,000 at a temperature of from about 180 F. to about 265 F. for not more than about one and one-half hours, and then rapidly reducing the temperature to below about 170 F.

2. A bitumen composition described in claim 1 in which the aliphatic polyamine is an alkylene polyamine containing at least two primary amino nitrogen atoms.

3. A bitumen composition described in claim 1 which the aliphatic polyamine is an alkylene diamine.

4. A bitumen composition described in claim 1 which the aliphatic polyamine is ethylene diamine.

5. A bitumen composition described in claim 1 which the aliphatic polyamine is propylene diamine.

6. A bitumen composition described in claim 1 which the aliphatic polyamine is diethylene triamine.

7. A bitumen composition described in claim 1 in which the aliphatic polyamine is a polyamine mixture comprising essentially diethylene triamine and minor amounts of ethylene diamine and triethylene tetramine.

8. A bitumen composition described in claim 1 in which the aliphatic polyamine is trialkylene tetramine.

9. A bitumen composition described in claim 1 in which the aliphatic polyamine is triethylene tetramine.

10. A bitumen composition described in claim 1 in which the aliphatic polyamine has the general formula RNH(CH2)3NH2, in which R is an aliphatic group containing from about 10 to about 18 carbon atoms, said polyamine being obtained by condensing a C12 to C18 aliphatic amine with acrylonitrile and hydrogenating the condensation product to the corresponding diamine.

11. A composition of matter as described in claim 1 in which said reaction product is diluted with from about 10% to about 50% of an aromatic-rich hydrocarbon solvent having a boiling point above about 220 F.

12. A composition of matter consisting essentially of a major proportion of a bitumen, and from about 0.25% to about 5% of the oil-soluble reaction product substantially free of amido groups obtained by reacting an alkylene polyamine having 2 to 6 carbon atoms in the alkylene group and a polymerized fatty acid from vegetable oils containing at least one double bond per molecule and having a molecular weight of from about 400 to about 2,000 at a temperature of from about 180 F. to about 265 F. for not more than one and one-half hours, and then rapidly reducing the temperature to below about F.

13. A roadway construction composition resistant to water stripping comprising a mineral aggregate admixed with a composition consisting essentially of a major proportion of a bitumen, and from about 0.25 to about 5% of the oil-soluble reaction product substantially free of amido groups obtained by reacting an alkylene polyamine having 2 to 6 carbon atoms in the alkylene group and a polymerized unsaturated fatty acid from vegetable oils having a molecular weight of from about 400 to about 2,000 at a temperature of from about F. to about 265 F. for not more than about one and one-half hours, and then rapidly reducing the temperature to below about 170 F.

14. A composition of matter consisting essentially of a major proportion of a bitumen, and from about 0.25 to about 5% of the oil-soluble reaction product substantially free of amido groups obtained by reacting an aliphatic alkylene polyamine having 2 to 6 carbon atoms in the alkylene group and a polymerized, polyunsaturated fatty acid from vegetable oils at a temperature of from about 180 F. to about 265 F. for not more than about one and one-half hours, and then rapidly reducing said temperature to below about 170 F., said polymerized, polyunsaturated fatty acid containing a predominant proportion of dilinoleic acid and a minor proportion of trilinoleic acid and having a molecular weight between about 560 and 840.

References Cited in the file of this patent UNITED STATES PATENTS 2,426,220 Johnson Aug. 26, 1947 2,450,940 Cowan Oct. 12, 1948 2,508,924 Mertens May 23, 1950 2,540,678 Kelley Feb. 6, 1951 FOREIGN PATENTS 917,518 France Jan. 9, 1947 

1. A COMPOSITION OF MATTER CONSISTING ESSENTIALLY OF A MAJOR PROPORTION OF A BITUMEN, AND FROM ABOUT 0.25% TO ABOUT 5% OF THE OIL-SOLUBLE REACTION PRODUCT SUBSTANTIALLY FREE OF AMIDO GROUPS OBTAINED BY REACTING AN ALKYLENE POLYAMINE HAVING 2 TO 6 CARBON ATOMS IN THE ALKYLENE GROUP AND A POLYMERIZED UNSATURATED FATTY ACID FROM VEGETABLE OILS HAVING A MOLECULAR WEIGHT BETWEEN ABOUT 400 AND 2,000 AT A TEMPERATURE OF FROM ABOUT 180* F. TO ABOUT 265* F. FOR NOT MORE THAN ABOUT ONE AND ONE-HALF HOURS, AND THEN RAPIDLY REDUCING THE TEMPERATURE TO BELOW ABOUT 170* F. 